Lennox SIGNATURE SLP99UH090XV48C User Manual

Page 1
INSTALLATION
INSTRUCTIONS
SLP99UHV
507999-01
10/2021
Supersedes 08/2021
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal
injury or loss of life. Installation and service must be
performed by a licensed professional HVAC installer or
equivalent, service agency, or the gas supplier.
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be
ignored. When you see this symbol on labels or in man-
uals, be alert to the potential for personal injury or death.
CAUTION
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
NOTICE
A thermostat is not included and must be ordered
separately.
• A communicating thermostat must be used in
communicating applications.
• In non-communicating applications, the Lennox
ComfortSense
®
7500 thermostat may be used, as well
as other non-communicating thermostats.
In all cases, setup is critical to ensure proper system
operation.
Field wiring for both communicating and non-
communicating applications is illustrated in diagrams,
which begin on Page 35
©
2021 Lennox Industries Inc.
Dallas, Texas USA
DAVE LENNOX SIGNATURE
®
COLLECTION GAS FURNACES
UP/FLOW HORIZONTAL AIR DISCHARGE
Contents
Unit Dimensions .............................................................2
Parts Arrangement..........................................................3
SLP99UHV Gas Furnace ...............................................4
Shipping and Packing List ..............................................4
Safety Information ..........................................................4
Use of Furnace as Construction Heater .........................5
General ...........................................................................6
Installation - Setting Equipment ......................................6
Filters ............................................................................10
Duct System .................................................................10
Pipe Fittings Specications...........................................13
Joint Cementing Procedure .......................................... 14
Venting Practices ..........................................................15
Vent Pipe Guidelines ....................................................15
Gas Piping ....................................................................30
Electrical .......................................................................33
Integrated Control .........................................................41
Unit Start-Up .................................................................50
Gas Pressure Measurement ........................................51
Operating Pressure Signal Measurement ....................52
Proper Combustion.......................................................53
High Altitude Information ..............................................53
Other Unit Adjustments.................................................53
Heating Sequence of Operation ...................................54
Service..........................................................................56
Repair Parts List ...........................................................58
Integrated Control Diagnostic Codes............................59
Conguring Unit Size Codes ........................................62
Troubleshooting: Heating Sequence of Operation .......63

Lennox SIGNATURE SLP99UH090XV48C Specifications

General

Model	SLP99UH090XV48C
Type	Gas Furnace
Efficiency Rating	Up to 99% AFUE
Heating Capacity	Up to 90, 000 BTU/h
Blower Type	Variable Speed
Fuel Type	Natural Gas
Stages	Modulating
Warranty	10-Year Limited Warranty on covered components

Summary

Installation Instructions SLP99UHV

SLP99UHV Gas Furnace

Safety Information

General safety warnings and precautions for furnace installation.

General

Installation - Setting Equipment

Procedures for initial setup and configuration of the furnace.

Use of Furnace as Construction Heater

Conditions and requirements for using the furnace for construction heating.

Installation - Setting Equipment

Upflow Applications

Specific instructions for setting up the furnace in an upflow configuration.

Venting Practices

Vent Pipe Guidelines

Rules and recommendations for installing vent pipes.

Guidelines for Vent Terminations

Gas Piping

Leak Check

Procedure for checking all field-installed piping connections for gas leaks.

Electrical

Communicating Enabled Furnace and Non-Communicating Outdoor Unit

FIGURE 52

Wiring diagram for communicating thermostat systems.

TABLE 15

Field Wiring Connections for Non-Communicating Thermostat Applications

Table detailing field wiring connections for non-communicating thermostats.

TABLE 16

Heating Operation DIP Switch Settings

Settings for DIP switches controlling heating operation.

Indoor Blower Operation DIP Switch Settings

Heating Mode Blower Speed

TABLE 22

TABLE 23

Diagnostic LED (FIGURE 55)

Description of the seven-segment diagnostic LED and its codes.

Field Test Mode

Procedure for entering and using the field test mode.

TABLE 24

Allowable Heating Speeds

TABLE 26

Cooling operating sequence for SLP99UHV with single-stage outdoor unit.

TABLE 27

OPERATING SEQUENCE SLP99UHV and Two-Speed Outdoor Unit

Cooling operating sequence for SLP99UHV with two-speed outdoor unit.

Unit Start-Up

Priming Condensate Trap

Gas Valve Operation (FIGURE 56)

Instructions and diagram for operating the gas valve.

Gas Pressure Measurement

Supply Pressure Measurement

Manifold Pressure Measurement (FIGURE 57)

Procedure for measuring manifold pressure at the gas valve.

Operating Pressure Signal (Delta P) Measurement (FIGURE 58)

Procedure for measuring the operating pressure signal (Delta P).

Proper Combustion

High Altitude Information

Pressure Switches (Two)

Temperature Rise

Heating Sequence of Operation

Description of the furnace's heating sequence of operation.

Applications Using a Two-Stage Thermostat

B - Heating Sequence -- Control Thermostat Selection DIP switch in "Variable Capacity" Position

Heating sequence for variable capacity mode with a two-stage thermostat.

Applications Using A Single-Stage Thermostat

Heating sequence for single-stage thermostat applications.

Service

Annual Furnace Maintenance

Routine maintenance checks recommended for the furnace.

Integrated Control Diagnostic Codes

Code

List of diagnostic codes and their corresponding status of equipment.

Configuring Unit Size Codes

Power-Up

Procedure for configuring the unit size code during initial power-up.

Troubleshooting: Heating Sequence of Operation

IGNITION AND CALL FOR LOW FIRE WITH TWO-STAGE THERMOSTAT

Troubleshooting steps for ignition and low fire operation with a two-stage thermostat.

Troubleshooting: Heating Sequence of Operation (continued)

CALL FOR HIGH FIRE WITH TWO-STAGE THERMOSTAT

Continuation of troubleshooting steps for high fire operation with a two-stage thermostat.

IGNITION AND CALL FOR HEAT WITH SINGLE-STAGE THERMOSTAT

Troubleshooting steps for ignition and heat call with a single-stage thermostat.

Troubleshooting: Cooling Sequence of Operation

CALL FOR COOLING

Troubleshooting steps for when the system receives a call for cooling.

Troubleshooting: Continuous Fan Sequence of Operation

CONTINUOUS LOW SPEED INDOOR BLOWER SEQUENCE OF OPERATION

Sequence of operation for continuous low speed indoor blower.